process variable
Now, we'll continue the last topic that is about process variable. For attention, article in this blog is talk about instrumentation in pulp and paper industry. But the principles of instrumentation in all industry must be same. The chapter write what we call as process variable in main thing, cause in next chance we'll discuss it one by one.
1. Pressure
Pressure ( symbol= p ) is the force per unit area applied on a surface in a direction perpendicular to that surface. Mathematically : p = F/A, where F is the normal force and A is the area..
Pressure is a scalar, and has SI units of Pascal, 1 Pa = 1N/m2
2. Flow meters
Measuring the flow of liquids is a critical need in many industrial plants. In some operatons, the ability to conduct accurate flow measurement is so important that it can make the difference between making a profit or taking a loss. With most liquid measurement instruments, the flow rate is determined inferentially by measuring the liquids velocity or the change in kinetic energy. Velocity depends on the pressure differential that is forcing the liquid through a pipe or conduit. Because the pipe's cross sectional area is known and remains constant, the average velocity is an indicaton of the flow rate. The basic relationship for determining the liquid's flow rate in such cases is : Q = VxA
Q = liquid flow through the pipe
A = average velocity of the flow
V = cross-sectional area of the pipe
3. Temperature
Temperature, a measure of the quantity of heat in the object, usually measured on thermometer. Temperature can be measured via a diverse array of the sensors. All of them infer temperature by sensing come change in physical characteristic. Six types with which the engineer is likely to come into contact are thermocouples, RTDs and thermistor, infrared radiator, bimetallic devices, liquid expansion devices, and change of state devices.
4. Level
These are two ways of measuring level :
Direct methods, which use the varying of the liquid as a means of obtaining the measurements. Idirect methods, which use a variable that change with the liquid level, to actuate the measuring mechanism.
5. Density
For a fluid, density is define as the mass per unit volume ( grams per cubic centimeter ).
Specific gravity scale, is the ratio of the density of the fluid to density water.
6. Radiation
Radiation in physics is the process of emitting energy in the form of waves or particles. Various types of radiation maybe distinguished, depending on the properties of the emitted energy/matter, the type of emission source, properties and purposes of the emission, etc. Whwn used by general public, the word radiation commonly refers ro ionizing radiation.
7. Electric Current
Electric current is by definition the flow of the electric charge. The SI unit of electric current is ampere ( A ), which is equal to a flow of one coulomb of charge per second.
8. Voltage
Volatage is the difference of electrical potential between two points of an electrical network,expressed i volts. It is measure of the capacity of an electric field to cause an electric current in an electric conductor.
9. Inductance
Inductance ( or electric inductance ) is a measure of the amount o magnetic fluk produced for a given electric current. The SI unit of inductance is the Henry ( H ), the symbol L is used for inductance has rhe following relationship : L is the inductance in henrys,
i is current i amperes
10. Capacitance
Capacitance is a measure of the amount of electric charge stored ( or separated ) for a given electric potential. In a capacitors, there are two conducting electrodes which are insulated from one another. The charge on the electrodes is +Q and -Q, and V represent the potential difference between the electrodes. The SI unit of capacitance is the farad; 1 farad = 1 coulomb per volt.
11. Frequency
Frequency is the measurement of the number of times that a repeated event occurs per unit o the time. It is also defined as the rate of change of phase of a sinusoidal waveform.
1. Pressure
Pressure ( symbol= p ) is the force per unit area applied on a surface in a direction perpendicular to that surface. Mathematically : p = F/A, where F is the normal force and A is the area..
Pressure is a scalar, and has SI units of Pascal, 1 Pa = 1N/m2
2. Flow meters
Measuring the flow of liquids is a critical need in many industrial plants. In some operatons, the ability to conduct accurate flow measurement is so important that it can make the difference between making a profit or taking a loss. With most liquid measurement instruments, the flow rate is determined inferentially by measuring the liquids velocity or the change in kinetic energy. Velocity depends on the pressure differential that is forcing the liquid through a pipe or conduit. Because the pipe's cross sectional area is known and remains constant, the average velocity is an indicaton of the flow rate. The basic relationship for determining the liquid's flow rate in such cases is : Q = VxA
Q = liquid flow through the pipe
A = average velocity of the flow
V = cross-sectional area of the pipe
3. Temperature
Temperature, a measure of the quantity of heat in the object, usually measured on thermometer. Temperature can be measured via a diverse array of the sensors. All of them infer temperature by sensing come change in physical characteristic. Six types with which the engineer is likely to come into contact are thermocouples, RTDs and thermistor, infrared radiator, bimetallic devices, liquid expansion devices, and change of state devices.
4. Level
These are two ways of measuring level :
Direct methods, which use the varying of the liquid as a means of obtaining the measurements. Idirect methods, which use a variable that change with the liquid level, to actuate the measuring mechanism.
5. Density
For a fluid, density is define as the mass per unit volume ( grams per cubic centimeter ).
Specific gravity scale, is the ratio of the density of the fluid to density water.
6. Radiation
Radiation in physics is the process of emitting energy in the form of waves or particles. Various types of radiation maybe distinguished, depending on the properties of the emitted energy/matter, the type of emission source, properties and purposes of the emission, etc. Whwn used by general public, the word radiation commonly refers ro ionizing radiation.
7. Electric Current
Electric current is by definition the flow of the electric charge. The SI unit of electric current is ampere ( A ), which is equal to a flow of one coulomb of charge per second.
8. Voltage
Volatage is the difference of electrical potential between two points of an electrical network,expressed i volts. It is measure of the capacity of an electric field to cause an electric current in an electric conductor.
9. Inductance
Inductance ( or electric inductance ) is a measure of the amount o magnetic fluk produced for a given electric current. The SI unit of inductance is the Henry ( H ), the symbol L is used for inductance has rhe following relationship : L is the inductance in henrys,
i is current i amperes
10. Capacitance
Capacitance is a measure of the amount of electric charge stored ( or separated ) for a given electric potential. In a capacitors, there are two conducting electrodes which are insulated from one another. The charge on the electrodes is +Q and -Q, and V represent the potential difference between the electrodes. The SI unit of capacitance is the farad; 1 farad = 1 coulomb per volt.
11. Frequency
Frequency is the measurement of the number of times that a repeated event occurs per unit o the time. It is also defined as the rate of change of phase of a sinusoidal waveform.
Posting Komentar
